Method of desulfurizing crude oil



Patented Sept. 12, 1950 METHOD OF .DESULFURIZING CRUDE OE Raymond J. Strawinski, Long Beach, Calif., as-

signor' to Texaco Development Corporation, New York, N. Y., a corporation of Delaware No Drawing. Application July 23, 1947,

Serial No. 763,173

4 Claims. (Cl. 195-3) This invention relates to a method for desulfurizing crude oil and like substances.

Crude oil. in some cases, is characterized by the presence of objectionable quantities of sulfur compounds which must be removed or substantially reduced in amount, dependent on the uses of the final products, to eliminate any corrosive efiect of the final products when put in use. Such sulfur compounds are further objectionable in such final products as fuels for internal combustion engines in that they reduce the efficiency of anti-knock compounds such as tetraethyl lead, and will when used alone, reduce the octane number of the fuel. Such crudes cannot be handled by conventional refining methods because of the corrosive effect of the sulfur compounds. Modification of the usual refining steps plus additional steps are required in the refining of such crudes to either abstract the sulfur compounds or reduce them to unobjectionable amounts. Such process modifications require extensive apparatus, involve corrosion problems, and add materially to the cost of the final products. Whil it is known that certain microorganisms will attack sulfur compounds and effect their conversion to easily removable sulfur compounds such as hydrogen sulfide and water-soluble sulfur compounds, procedures along the line of using such microorganisms in crude oils to remove and reduce the sulfur compounds therein have not been utilized, apparently because of the propensity of such microorganisms for the hydrocarbons in the crude and the consequent loss of desired constituents of the crude.

It is an object of this invention to provide a novel method wherein such microorganisms can be-used to advantage in desulfurizing crude oil and. fractions thereof without any material consumption of the hydrocarbons therein.

A further object of this invention is to provide a novel method whereby the sulfur compounds of crude oils and fractions thereof can be convertedinto easily removable products in a relatively simple manner, the processed crude then being capable of refining by conventional methods to produce products characterized by a substantial absence of sulfur compounds.

In brief, the present invention maybe described as involving the treatment of crude oil, topped crude or fractions thereof, with microorganisms inherently capable of consuming the sulfur compounds therein and converting themto products such as hydrogen sulfide or other products capable of easy separation from the crude, and capable also of converting hydrocarbons of the crude in a similar manner, the lastnamed function being substantially prevented by the presence of a diverting agent or divertant which functions to divert the hydrocarbon-con- 2 suming action of the microorganisms from the hydrocarbons.

The microorganisms employed may be obtained from mixtures such as occur in nature preferably where crude oil or petroleum products have been stored or spilled. They may be found in oilsoaked soils, water from the bottom of storage tanks in which crudeoil or petroleum products have been stored, the water of petroleum separation tanks and sedimentation ponds. They also occur in sea water, marine bottom deposits, garden and field soils, industrial waste and sewage disposal waters and like waste material. Such mixtures contain an undetermined number of different species of microorganisms both of the aerobic and anaerobic types. Such mixtures contain, for example, species of Pseudomonas, Achromobacter, Alcaligenes, Proactinomycetes, Actinomycetes, Bacillus, Bacterium, Clostridium, Micrococci, Penicillium, Aspergillus, sulfate-reducers, methane oxidizers, yeast and yeast-like organisms. Any of such natural mixtures, or combinations thereof, when propagated under laboratory conditions, an example of which is given below, will yield a mixture of organisms capable of consuming or converting the sulfur compounds of the substance to be treated can be used, it being understood that the invention is not limited to the use of any particular mixture, class orv species of microorganisms except that it or they be capable of consuming the sulfur compounds or converting them to easily removable sulfur compounds. Microorganisms from animal, marine, and vegetable sources can likewise be used as well as microorganisms from waste materials such as sewage.

The fact that a mixture, class or species of microorganisms may also be capable of consuming desired hydrocarbons, and this is usually the case, is of no moment as regards the process of this invention since this action is substantially nullified by the presence of a diverter or divertant that is more attractive to the carbon-consuming propensity of other microorganisms than the hydrocarbons in the oil.

The diverter or divertant employed may be defined according to its principal characteristic, that is, its ability to attract the carbon-consuming microorganisms more than the hydrocarbons of the oil. Preferably a carbon-containing compound or mixture thereof is desired. The use of carbohydrates such as monosaccharides, polysaccharides such as starches, celluloses, hemi- .celluloses, and proteins such as peptone, de-

pendent upon the particular organism employed, is contemplated. Industrial wastes, containing such compounds or mixtures thereof, can be employed.

As an example of the method of this invention, a water sample taken from the bottom of an oil tank was incubated in a mixture of approximately 1 per cent crude and 99 per cent nutrient solution, the water sample being added in an amount or approximately 5 per cent of the mixture. No sugar was present; The nutri' ent solution was of unusual character in that it contained no inorganic sulfur other than that contaminating the chemicals added which in final concentration was negligible for practical purposes. Therefore, it is substantially correct to consider that the only sulfur available was present in the oil. The mineral content of the solution was of approximately the-following composi-.- tion:

The addition of certain ions in trace amounts such as copper, mercury, zinc, bismuth, iodine to the medium will stimulate the activity of microorganisms. Care must be exercised in the amount added since when they are present in more than traces they tend to poison the microorganism.

The above compounds in the quantities noted were added to 1000 ml. of distilled water, and the pH adjusted so that after sterilization, it was about 7. The resulting complete combination was incubated for five to seven days. After incubation a portion of the resultant growth was then seeded into another bottle complete in all respects but without the original water sample taken from the bottom of oil tank. Four to six such subcultures were made during which procedure contaminating nutrients and microorganisms incapable of utilizing sulfurin oil, were eliminated by dilution resulting ina mixed culture capable of consuming sulfur in oil in a medium substantially as described. A portion of the resultant culture was streaked on the surface of a solid substrate such as sterile nutrient agar arid allowed to remain until good colony formation was obtained, three to four days being required, the temperature being maintained at about 28-30 C. A selected colony was incubated fromgmedium to medium (a liquid medium of the mineral saltsmix. The crude in this particular case was socalled Arabian crude which contains sulfur compounds that have been found to be exceedingly resistant to conventional methods of removal. Enough of the previously prepared incubated culture of microorganisms was added to the above sterile crude and nutrient mixture in an amount of about 5 per cent by volume of the whole, the mixture being slowly and continuously stirred without aeration except through the surface at about 28 C. at a pH of approximately '7. The

sulfur content of the original crude and the suifur content of the crude after about four days treatment were determined by the Shell-Braun sulfur apparatus. the net reduction in the sulfur content of crude processed being about 12.5 per cent by weight.

In the above example, the microorganism was of the Pseudomonas type which was designated II. with other microorganisms, it is to be understood that other divertants may be more suitable and that the optimum conditions as to temperature. times and pH may be different. Such factors can readily be determined by experimental methods well known in the art.

' The use of other carbohydrates such as starch and cellulose as divertants is contemplated as well as animal, marine and vegetable matter or waste products, it being desirable that the material be iree of sulfur or that it contain sulfuronly in forms not affected by the microorganisms employed.

The .oil treated may be in crude form or partially treated or refined. Fractions thereof in various stages of processing can be treated by the present method.

Obviously, many modifications and variations of the invention, as above set forth may be made without departing from the spirit and scope thereof and only such limitations should be imposed as are indicated in the appended claims.

I claim: a

1. A method of treating crude oil to reduce the sulfur content thereof comprising the steps of combining crude oil with a mineral salt nutrient medium in a proportion of about 5% crude oil to nutrient medium by volume, adding a monosaccharide in a proportion of about 2% by weight and inoculating the resultant mix with a carbonand sulfur-consuming microorganism.

2. A method of treating crude oil, topped crude, fractions thereof and partially treated or refined oils to reduce the sulphur content thereof comprising the steps of subjecting the oil to the action of one or more carbon-consuming and sulphur-consuming microorganisms in the presence of a diverter capable of and present in sufiicient amount to divert substantially completely the carbon-consuming action of the microorganisms from the carbon content of the oil, said diverter being a compound selected from a group consisting of monosaccharides and polysaccharides.

3. The method of .claim 2 wherein the oil is treated in a substantially sulphur free medium.

4. The method of claim 2 wherein the diverter is dextrose.

RAYMOND J. STRAWINSKI.

REFERENCES CITED The following references are of record in the file of this patent: v

UNITED STATES PATENTS Number Name Date 1,753,641 Beckman Apr. 8, 1930 1,835,998 Giron Dec. 8, 1931 2,056,668 Bavin et a1 Oct. 6, 1936 OTHER REFERENCES Les Matieres Grasses, Oct. 15, 1924, pages 6936 6940, published by the Petroleum Institute of the University of Strasbourg.

Chem. Abstr. 1933. pa e 2173, by Aquino. 

1. A METHOD OF TREATING CRUDE OIL TO REDUCE THE SULFUR CONTENT THEREOF COMPRISING THE STEPS OF COMBINING CRUDE OIL WITH A MINERAL SALT NUTRIENT MEDIUM IN A PROPORTION OF ABOUT 5% CRUDE OIL TO 95% NUTRIENT MEDIUM BY VOLUME, ADDING A MONOSACCHARIDE IN A PROPORTION OF ABOUT 2% BY WEIGHT AND INOCULATING THE RESULTANT MIX WITH A CARBON- AND SULFUR-CONSUMING MICROORGANISM. 